Alternative colour scheme. Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
Classy golf-pants pattern, or crossed stripes if you will.
Source Will Monson
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
I have no idea what J Boo means by this name, but hey – it’s hot.
Source j Boo
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
A seamless pattern created from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Groovy Concentric Background 3
Source GDJ
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
A seamless background texture of old cardboard.
Source V. Hartikainen
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
ZeroCC tileable stone texture, edited from pixabay, CC0
Source Sojan Janso
Remixed from a drawing in 'Line and form", Walter Crane, 1914.
Source Firkin
Little x’es, noise and all the stuff you like. Dark like a Monday, with a hint of blue.
Source Tom McArdle
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Here's a tile-able wood background image for use in web design.
Source V. Hartikainen
Not sure if this is related to the Nami you get in Google image search, but hey, it’s nice!
Source Dertig Media
Utilising a bird from s-light and some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
You may use it as is, or modify it as you like.
Source V. Hartikainen
Prismatic Groovy Concentric Background No Black
Source GDJ
Another fairly simple design drawn in Paint.net and vectorized in Inkscape.
Source Firkin